Techniques for the liquid storage of platelets for transfusion will be evaluated. Initially, we will concentrate on developing a uniformly successful system for storage at 22 degrees C beyond 24 hours. Recent work has shown that containers with increased permeability to oxygen and carbon di ide are most beneficial. We will study pathways of metabolism of carbohydrate and other substrates as well as adenine nucleotide metabolism under these circumstances. Techniques for detecting antiplatelet factors and antibodies will be developed and contrasted in a variety of disease states. Clinically applicable methods for distinguishing among a variety of thrombocytopenic states will be explored with emphasis on platelet size measurements. Technical factors important in the determination of platelet size will be elucidated. Studies designed to elucidate the defect in platelet function in the myeloproliferative disorders will be carried out.